G'day and welcome to the forum!
Well, everything is a tradeoff, isn't it? You are sure to get a wide range of opinions here.
Here is a recent post from another mud member in Central America who drives a rig very similar to yours. I found his comments on tire sizes interesting.
Since you didn't mention having problems with getting stuck, and you did mention that your situation may change in 16 months, I think your wife is giving you the sensible (if boring) advice.
As for having two sets of wheels, I went that route. But changing all the wheels gets really old. I've actually been thinking about going the other way and trying a set of all-terrains once these tires are worn out.
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97 FZJ80, 78K, factory locked, OME 851/862, Slee tube sliders, Slee transfer skid, Painless Fab tube bumperettes, CDL/pin7, BFG 255/85R16 MTs